What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

46-01 Cooling Shroud Deleted

I have it cut out, fitted, clecoed and ready for fiberglass. Now I will remove it and fill the holes. A lot of time invested at this point, but if it's not needed there is no sense spending more time.
 
I have it cut out, fitted, clecoed and ready for fiberglass. Now I will remove it and fill the holes. A lot of time invested at this point, but if it's not needed there is no sense spending more time.

Hi Joe.. Do me a favor and call VANs first. I only note that the cooling shroud over the engine fins has been deleted on new power plant builds. I would think that if the cooling shroud is left in place over the engine fins it would trap heat without a properly installed forced air supply.

Jeff
 
Last edited:
Shroud or no shroud

My engine kit was delivered with the FF-1207 cooling shroud. Then in the meanwhile Van's got rid of it in their revised section 46. So I have the option wheter to install it or not.
If it does not make any real difference in cooling I d'rather skip to install it due to additional weight, easier access to the engine and to comply with the latest KAI rev.

So I am looking for pros and cons. and experience from pilots who fly the -12 without the shroud.
What I neither have found so far is an explanation why that shroud has become obsolete.
If anybody can enlight me about that, I very much appreciate it.
Thanks
 
Last edited:
A bit confusing

At the same stage. Vans have obviously done a cut and paste with the new section 46. Remove the ignition modules for example. Cannot see how to complete this without removing the manifold which is no longer called for. The drawings have not changed from the old version so no clues there. Am I missing something?
 
Folks ? here is my take on the issue.

Without knowing if there is a significant reason for Van?s decision like hot spots on the cylinders, ect, ?. I?m guessing the added benefit of having the cooling shroud versus the potential issues involved by Van?s requiring builders to remove the upper portion of the Rotax engine to install the shroud may have been a contributing factor in Van?s decision. Not to mention perhaps even behind the scenes Rotax warranty issues.

Cumulatively, there are many thousands of hours on RV-12?s with the cooling shroud in place without any adverse engine issues being reported that we are aware of ? so that is a known entity. That said, if I had the parts, I would install them.

Another thought comes to mind ? with the shroud off is there more of a potential for the rising heat from the cylinder fins to contribute to vapor lock at the carbs or fuel lines? ? especially after a short refueling stop or restroom break on hot days? I would think the shroud over the cylinders helps mitigate the negative effects of rising heat from the cylinders heating the fuel.
 
Folks ? here is my take on the issue.

Without knowing if there is a significant reason for Van?s decision like hot spots on the cylinders, ect, ?. I?m guessing the added benefit of having the cooling shroud versus the potential issues involved by Van?s requiring builders to remove the upper portion of the Rotax engine to install the shroud may have been a contributing factor in Van?s decision. Not to mention perhaps even behind the scenes Rotax warranty issues.

Cumulatively, there are many thousands of hours on RV-12?s with the cooling shroud in place without any adverse engine issues being reported that we are aware of ? so that is a known entity. That said, if I had the parts, I would install them.

Another thought comes to mind ? with the shroud off is there more of a potential for the rising heat from the cylinder fins to contribute to vapor lock at the carbs or fuel lines? ? especially after a short refueling stop or restroom break on hot days? I would think the shroud over the cylinders helps mitigate the negative effects of rising heat from the cylinders heating the fuel.

Interesting point regarding our "auto-gas preferred " engines...the cooling fairing being a heat shield below carb lines/bowls. Would like to hear from builders that haven't installed them who fly out of higher heat areas.
 
That's what Van's says

Thanks a lot for your inputs on that. Interesting thought about potential vapor locks. I also wonder what Synergy does in their serial production.
Anyhow, here's the answer from mothership to my question why the shroud has become obsolete.
Further testing showed insufficient benefit from the shroud so we eliminated it to keep the kit cost down, and reduce the work required.

I am still curious to get pireps using that setting.
 
Interesting point regarding our "auto-gas preferred " engines...the cooling fairing being a heat shield below carb lines/bowls. Would like to hear from builders that haven't installed them who fly out of higher heat areas.

The carb. float bowls already have a metal heat shield below them, called a drip tray.
The carbs are not above the aft cylinders so the shroud likely has little effect in shielding them while on the ground.
 
It sounds like there's no particular advantage to leaving the cooling shroud off? That is, if it's already installed, is there any reason to remove it?
 
That is, if it's already installed, is there any reason to remove it?

No
If there was, a notification would have been published recommending that they be removed.

More recent testing showed that the cyl. cooling was about the same with or without the shroud, so it was deleted to reduce the kit cost and reduce the chance of a builder induced problem during the engine disassembly and reassembly that was required to install it.
 
There is definitely an uneven cooling with this plenum design. The design itself is questionable in that it places the #2 cylinder in a corner away from the airflow - it is clear that the #2 cylinder would be starved for cooling until enough ram are were available to charge the plenum with a high enough pressure to force an even airflow.

As for disassembly of the engine - most know that at one point Rotax insisted that you not change your oil without the service class. Not sure if that's still true but I think it's safe to assume a fair number of folks have installed the engine without any Rotax training. It's not a difficult job - but I'm sure Rotax has concerns.
 
Back
Top